This invention relates to novel cyclopropyl compounds having biological activity, especially pesticidal and anti-inflammatory activity, and to a method of controlling weeds, insects, bacteria, fungi and other plant and animal pests using certain of these compounds.
A variety of compounds are current used for the control of insect and plant pests. Included among such pesticidal compounds are chlorinated hydrocarbons, arsenic compounds, mercury compounds and the like. While effective for their intended use, the safety of such materials is currently under question largely because of their poor biodegradability and high mammalian toxicity. Current trends in the chemical control of insect and plant pests call for inherently safer materials which degrade very rapidly to non-toxic substances once their purpose is accomplished. Accordingly, there is great demand for alternative broad spectrum pesticides which are suitable for the high volume usage entailed in agricultural applications.
Of the several types of biodegradable insecticides currently available, those compounds containing a cyclopropyl moiety, e.g., the derivatives of chrysanthemic acid, are of high potential utility inasmuch as these compounds have a relatively low initial mammalian toxicity and biodegrade under field conditions to non-toxic products. However, it has long been recognized that the preparation of compounds containing the cyclopropyl moiety is difficult inasmuch as this 3-membered ring is quite strained and is not readily established by ordinary chemical means. To date, compounds containing the cyclopropyl or cyclopropylcarbinyl group have had to be prepared by such methods as the zinc dust condensation of 1,3-dihalides, a method which yields only small amounts of the desired cyclopropyl derivatives because of intermolecular coupling reactions. The addition of &gt;C: fragments to olefins has also been employed, but requires expensive reactants. Accordingly, improved methods for preparing compounds containing the cyclopropyl moiety would be highly desirable, inasmuch as an economical route to such compounds would provide the basic intermediates for the preparation of a variety of biologically active cyclopropyl derivatives.
Another type of cyclopropyl compounds of interest are the p-(.alpha.-cyclopropyl)-tolyl acetic acids which have known anti-inflammatory properties but are difficult to prepare. Such compounds are described in the Journal of Medical Chemistry, Vol. 16, No. 5 at 487 (1973).
A variety of methods for preparing compounds containing the cyclopropyl moiety are known in the art. For example, Kuivila and Scrapa, J. Am. Chem. Soc. 92:23; 6990 (1970) teach the formation of cyclopropyl groups by an intramolecular electrophilic displacement caused by an internal carbonium ions. Davis et al., J. Organometal. Chem., 25 (1970) C13-C16 teach the reaction of certain organotin alcohols with certain chlorinating agents with cleavage of the organotin compound and elimination of cyclopropane. Sommer et al., J. Am. Chem. Soc., 71, 2056 (1949) teach the reaction of certain .gamma.-haloalkyl organosilicon compounds with alumium chloride to yield cyclopropane. Kuivila et al., J. Am. Chem. Soc., 93, 6990 (1970) disclose the formation of cyclopropyl groups by .alpha.,.omega. eliminations in a number of compounds including 3-toxyloxypropyltrimethylation.
From the foregoing it is seen that there are a variety of methods for preparing cyclopropyl compounds in the literature. However, the processes in the cited articles are not general in that they do not provide a variety of cyclopropyl compounds in high yields.
It is an object of this invention to provide a method for the preparation of cyclopropane compounds having functional substituents. It is a further object herein to provide cyclopropyl compounds having biological activity, especially pesticidal activity, and functionally substituted cyclopropane compounds having utility as intermediates in the preparation of biologically active materials. It is a further object herein to provide a method for synthesizing cyclopropane carboxylic acids such as chrysanthemic acid. These and other objects are obtained herein as will be seen from the following disclosure.